Packaging of absorbable materials in disposable boxes for use as pet sanitary stations is known. Ideally, the package serves the multiple purposes of transporting the material to the marketplace, holding the material during use, and disposing of the used material. For example, U.S. Pat. Nos. 3,154,052 and 3,743,170 describe how to package absorbable materials in foldable boxes that can be opened to form trays that are useful as a sanitary station for pets, and then closed to dispose of the used material. A disadvantage of these folding trays is that the absorbable material is not covered when the tray is open, therefore, the material remains visible during use and odors can readily escape. Although a separate cover can be mounted on the tray during use, it would be more convenient for pet owners that the package expand to form a covered tray. U.S. Pat. No. 3,085,550 illustrates a covered pet sanitary station which is not expandable. This sanitary station has the benefit of reducing odors but is too bulky for use as a disposable sanitary station.